1. Field of the Invention
The present invention is concerned with a portable timepiece like a wristwatch for instance, or the like, and relates especially to a timepiece in which there has been improved a structure retaining an edge member, to which a glass has been attached, to a front side of a case band.
2. Description of the Prior Art
Hitherto, in order to make a width of an annular edge member to which the glass has been attaches, in other words, a dimension corresponding to a dimension difference between an inner diameter and an outer diameter of the edge member, small (This is refereed to as an edge thinning of the edge member.), there is known a technique in which a screw fixing a bezel to the case band by the fact that it is inserted into the case band accommodating a timepiece movement and screwed to the bezel (edge member) is disposed in an inside than a gasket having been provided between the case band and the bezel while ensuring a waterproofness between them (e.g., refer to JP-A-2002-189084 Gazette (paragraphs 0008-0010, 0013-0019, FIG. 1-FIG. 5)).
This prior art is shown in FIG. 7. In FIG. 7, a reference numeral 1 denotes an armor case of one-piece structure, in which a case band 1a and a case back part 1b have been monolithically formed, and a reference numeral 2 a timepiece movement having been accommodated in the armor case 1 while being retained in a casing ring 3, respectively. To the timepiece movement 2, there are attached a dial 4 and timepiece hands 5. In FIG. 7, a reference numeral 6 denotes a bezel to which a glass 7 has been fixed, a reference numeral 8 a gasket, and a reference numeral 9 a screw, respectively. Further, a reference numeral 6a in FIG. 7 denotes a female thread part monolithically formed in a back side of the bezel 6 and having been fitted to the case band 1a from its front face side, and the screw 9 is screwed to this female thread part 6a from the back side. Additionally, a reference numeral 6b in FIG. 7 denoted a dial cover site having been formed while forming an inner periphery part of the bezel 6.
In this prior art, since the case band 1a and the bezel 6 are connected by the screw 9 and the gasket 8 has been nipped between them, an exchange of the gasket 8 is suitable possible. Not only it, there is no fear that a glass fixation part 6c of the bezel 6 is deformed by a stress following upon a screwing of the screw 9. Therefore, a fixation of the glass 7 to the bezel 6 may be performed by using an adhesive, or it is also possible to fix the glass 7 by pushing-in it into an inside of an attachment ring having an interference due to an elastic deformation by disposing this ring in an inner periphery of the glass fixation part 6c, and it is desirable in a point that choices for fixing the glass 7 increase.
In the technique of the Patent Document 1, since it is a constitution in which the screw 9 is meshed with the female thread part 6a having been provided in the bezel 6, this female thread part 6a has a threaded hole 6d. In order to ensure this threaded hole 6d, it is necessary to form the threaded hole 6d by a site surrounding the threaded hole 6d while having a thickness thicker than a certain degree. Since the bezel 6 has the threaded hole 6d like this, the edge thinning of this bezel 6 is not sufficient, so that there is a room for an additional improvement.
Concretely, a width T1 of the bezel 6, which has been shown in FIG. 7, in other words, a dimension T1 from the dial cover site 6b, which specifies an inner diameter of the bezel 6 and a parting dimension E of the dial 4, to an outer diameter of the bezel 6, is denoted by a value in which dimensions A-D and Z along a radial direction of each site of the bezel 6 have been totaled.
The dimension A is a dimension of the dial cover site 6b, the dimension B a dimension of a site from an inner periphery of the male thread part 6a to a center line of the threaded hole 6d, the dimension C a dimension of a site having contacted with the gasket 8, the dimension D a dimension of a site from an outer periphery of the gasket 8 to an outer periphery of the bezel 6, and the dimension Z is a dimension of a site from an inner periphery of the gasket 8 to the center line of the threaded hole 6d and, by this dimension Z, a disposition of the screw 9 is deviated to an inside of the gasket 8.
The width T1 of the bezel 6, which is formed by the total of the dimensions A-D and Z like these, is small in comparison with a constitution in which the screw 9 has been disposed in an outside of the gasket 8. However, since there is required the dimension Z for disposing the screw 9 in an inside of the gasket 8, it is not suitable for making the width T1 of the bezel 6 smaller to thereby perform the edge thinning.